Visualizing Precambrian Basement Tectonics beneath a Carbon Capture and Storage Site, Illinois Basin

Characterization of Precambrian basement tectonics using 3D reflection seismology is critical for fully constraining the geology of a carbon capture and storage (CCS) site. Our study applies state-of-the-art visualization and attribute analysis to a 3D seismic volume of the basement complex that underlies the Illinois Basin-Decatur Project (IBDP) CCS site. The most successful interpretative techniques used include geo-body analysis, X (east-west, cross-line)-directed amplitude change, and co-rendering (e.g., amplitude with semblance), integrated with gradient analysis. The 3D volume reveals a strong reflector deep within the basement complex that is interpreted to be a mafic sill, disrupted by a coherent pattern of prominent structural discontinuities. The discontinuities, which have a mutually orthogonal northwest-northeast trend, could have formed as part of the intrusion process, as tectonic faults, or a combination of both processes. Our preferred interpretation is that discontinuities are small fault...